jif 8edb95f274 Preserve MCP compatibility with older executors (#39979) ...

## Why

Older executors do not support resolving HTTP header values from their own
environment. Sending environment-backed bearer tokens to them can prevent MCP
servers from starting.

## What changed

- Advertise executor support for environment-backed HTTP headers with the
  `httpHeaderEnvVars` capability.
- Delegate bearer-token resolution only when the selected executor advertises
  that capability; otherwise, resolve tokens available in the host environment.
- Exclude executor-owned MCP servers that require environment-backed bearer
  tokens when the executor cannot resolve them, while retaining compatible
  host-owned and executor-owned servers.

## Testing

Added protocol and environment-variable coverage plus an end-to-end test that
simulates an older executor and verifies compatible MCP servers remain usable.

GitOrigin-RevId: 43545926f6f7e0f3b1091eb29d34647f6372bc4a

2026-08-21 17:21:30 +00:00

..

src

Preserve MCP compatibility with older executors (#39979)

2026-08-21 17:21:30 +00:00

BUILD.bazel

protocol: separate app and exec RPC ownership (#29714)

2026-06-23 22:37:31 +00:00

Cargo.toml

Preserve JSON number precision in exec-server RPC messages (#33031)

2026-07-14 10:26:52 +00:00